The present invention relates to an improved suspension system for an automobile, more particularly to an automotive coil spring suspension system with both shock absorption and anti-swing functions.
FIG. 1 illustrates a typical automotive suspension arrangement using a coil spring at the front wheels of an automobile. The weight of the vehicle applies an initial pressure on the springs thereof. When the wheels encounter irregularities in the road, the springs further compress or expand to absorb most of the shock. The suspension system which is provided at the rear wheels of an automobile is relatively simple in most vehicles. However, the suspension system provided at the front wheels of an automobile is considerably more complex because said front wheels must swing from side to side to allow for steering. In view of this, multi-point attachments are provided that permit the wheels of a car to move up and down and still be turned from side to side for steering purposes. In FIG. 1, a conventional automotive, front-wheels suspension system referred to as a "Macpherson front suspension," is shown. In this system, a shock absorber 11 is used at each front wheel of the automobile to restrain spring 12 movement and prevent prolonged oscillation. The shock absorber 11 contains a piston that moves in a cylinder as the automobile wheel moves up and down with respect to the automobile frame. The MacPherson suspension is a coil-spring system in which the shock absorber is located inside the spring. This system requires neither upper and lower suspension nor control arms and is widely used in smaller, front-wheel-drive vehicles because of the simplicity, low weight, low cost and compactness thereof.
It has been noted that in a conventional automotive front wheel suspension system, the design of the coil spring differs greatly from that of the spring of the Macpherson system. In the conventional system the coil spring is required to be as soft as possible in order to respond to the continuous irregularities of the surface of the road. However, when a vehicle is steered in a certain direction, the coil spring must maintain a maximum rigidity in order to prevent the car from swinging away from the intended course. The fulfillment of both of these requirements in a single coil spring necessarily makes the the manufacture thereof very difficult.